U.S. patent number 4,648,810 [Application Number 06/734,025] was granted by the patent office on 1987-03-10 for control apparatus for a positive displacement reciprocating pump.
This patent grant is currently assigned to Barmag Barmer Maschinenfabrik AG. Invention is credited to Siegfried Hertell, Heinz Schippers.
United States Patent |
4,648,810 |
Schippers , et al. |
March 10, 1987 |
Control apparatus for a positive displacement reciprocating
pump
Abstract
A positive displacement reciprocating pump for conveying a
liquid or gaseous fluid is disclosed and which comprises a fluid
enclosure having a movable piston means mounted therein which
sealably divides the enclosure into a pumping chamber on one side
and an actuating chamber on the other side. The piston means may
comprise either a slideable piston or a flexible diaphragm. An
inlet valve and a separate outlet valve are each connected to the
pumping chamber, and a control system is provided for
intermittently supplying a pressurized working fluid to the
actuating chamber so as to intermittently move the piston means in
the discharge direction, with the piston means being moved in the
opposite or suction direction by either the pressure of the fluid
being conveyed, or a suitable spring. The control system for
advancing the piston means in the discharge direction includes a
source of pressurized working fluid, a working fluid line extending
between the source and the actuating chamber, and a valve
operatively connected to the working fluid line for intermittently
opening the line to a discharge tank or the like to release the
pressure therein.
Inventors: |
Schippers; Heinz (Remscheid,
DE), Hertell; Siegfried (Radevormwald,
DE) |
Assignee: |
Barmag Barmer Maschinenfabrik
AG (Remscheid, DE)
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Family
ID: |
27189629 |
Appl.
No.: |
06/734,025 |
Filed: |
May 14, 1985 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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434172 |
Oct 13, 1982 |
4523901 |
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Foreign Application Priority Data
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Oct 17, 1981 [DE] |
|
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3141359 |
Nov 28, 1981 [DE] |
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3147235 |
Apr 1, 1982 [DE] |
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3212112 |
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Current U.S.
Class: |
417/383; 92/129;
91/50; 91/313; 417/395 |
Current CPC
Class: |
F04B
43/073 (20130101); F25B 15/025 (20130101) |
Current International
Class: |
F04B
43/073 (20060101); F04B 43/06 (20060101); F25B
15/02 (20060101); F04B 043/06 (); F04B 045/00 ();
F01L 075/02 (); F16J 001/10 () |
Field of
Search: |
;417/395
;91/47,50,313,304 ;92/129 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Obee; Jane E.
Attorney, Agent or Firm: Bell, Seltzer, Park &
Gibson
Parent Case Text
This application is a division, of application Ser. No. 434,172,
filed Oct. 13, 1982, now U.S. Pat. No. 4,523,901.
Claims
That which is claimed is:
1. A positive displacement reciprocating pump for conveying a
liquid or gaseous fluid, and comprising
a fluid enclosure,
movable piston means sealably disposed in said enclosure and
dividing the enclosure into a pumping chamber on one side of the
piston means and an actuating chamber on the other side thereof,
and including spring biasing means for biasing said piston means
toward said actuating chamber,
an inlet valve and a separate outlet valve each communicating with
said pumping chamber,
control means for intermittently supplying a pressurized working
fluid to said actuating chamber so as to intermittently move said
piston means in a direction toward said pumping chamber and thereby
discharge the conveyed fluid from such chamber, said control means
including a source of pressurized working fluid, a working fluid
line extending between said source and said actuating chamber,
valve means operatively connected to said working fluid line and
including a slide which is movable between an open position wherein
said line is opened to a discharge tank means to release the
pressure therein, and a closed position wherein the pressure of
said working fluid is maintained in said line and delivered to said
actuating chamber, and pre-control means controlled by the position
of said piston means for effecting movement of said slide to said
open position upon said piston means essentially reaching its
maximum movement toward said pumping chamber, and for moving said
slide to said closed position upon said piston means essentially
reaching its maximum movement in the opposite direction, said
pre-control means including spring means for biasing said slide of
said valve means toward its closed position, and pre-control valve
means for periodically biasing said slide toward its open position,
said pre-control valve means including a valve housing extending
along a direction aligned with the direction of movement of said
piston means, a rod having a control collar fixed thereto slideably
mounted in said valve housing, and means operatively
interconnecting said piston means and said rod and including lost
motion interconnection means whereby said rod is moved by said
piston means only adjacent the ends of the opposite movements of
said piston means.
2. The pump as defined in claim 1 wherein said pre-control valve
means further includes
a first line extending between said valve housing and the side of
said slide opposite said spring means,
a second line extending between said valve housing and said source
of pressurized working fluid,
a third line extending between said valve housing and said
discharge means tank,
and wherein said rod and control collar are movable between a
neutral position closing said first line, a position on one side of
said neutral position wherein communication is opened between said
first and second lines so that the pressure of said working fluid
acts to bias said slide toward its open position, and a further
position on the other side of said neutral position wherein
communication is opened between said first and third lines so that
the biasing force applied to said slide toward its open position is
released.
3. The pump as defined in claim 1 wherein said piston means
comprises a flexible diaphragm.
4. A positive displacement reciprocating pump for conveying a
liquid or gaseous fluid, and comprising
a fluid enclosure,
movable piston means sealably disposed in said enclosure and
dividing the enclosure into a pumping chamber on one side of the
piston means and an actuating chamber on the other side
thereof,
an inlet valve and a separate outlet valve each communicating with
said pumping chamber,
control means for intermittently supplying a pressurized working
fluid to said actuating chamber so as to intermittently move said
piston means in a direction toward said pumping chamber and thereby
discharge the conveyed fluid from such chamber, said control means
including a source of pressurized working fluid, a working fluid
line extending between said source and said actuating chamber,
valve means operatively connected to said working fluid line and
including a slide which is movable between an open position wherein
said line is opened to discharge tank means to release the pressure
therein, and a closed position wherein the pressure of said working
fluid is maintained in said line and delivered to said actuating
chamber, and pre-control means controlled by the position of said
piston means for effecting movement of said slide to said open
position upon said piston means essentially reaching its maximum
movement toward said pumping chamber, and for moving said slide to
said closed position upon said piston means essentially reaching
its maximum movement in the opposite direction, said pre-control
means including spring means for biasing said slide of said valve
means toward its closed position, and pre-control valve means for
periodically biasing said slide toward its open position, said
pre-control valve means including a valve housing extending along a
direction aligned with the direction of movement of said piston
means, a rod having a control collar fixed thereto slideably
mounted in said valve housing, and means operatively
interconnecting said piston means and said rod, a first line
extending between said valve housing and the side of said slide
opposite said spring means, a second line extending between said
valve housing and said source of pressurized working fluid, a third
line extending between said valve housing and said discharge tank
means, and wherein said rod and control collar are movable between
a neutral position closing said first line, a position on one side
of said neutral position wherein communication is opened between
said first and second lines so that the pressure of said working
fluid acts to bias said slide toward its open position, and a
further position on the other side of said neutral position wherein
communication is opened between said first and third lines so that
the biasing force applied to said slide toward its open position is
released.
5. The pump as defined in claim 4 wherein said means operatively
interconnecting said piston means and said rod comprises lost
motion interconnection means whereby said rod is moved by said
piston means only adjacent the ends of the opposite movements of
said piston means.
6. The pump as defined in claim 4 wherein said piston means
comprises a flexible diaphragm, and spring biasing means for
biasing said flexible diaphragm toward said actuating chamber.
7. The pump as defined in claim 4 wherein said pre-control means
further comprises biasing means for biasing said rod toward said
neutral position thereof.
Description
The present invention relates to a positive displacement
reciprocating pump adapted to convey a liquid or gaseous substance,
and more particularly, to a novel control apparatus by which the
reciprocating operation of the pump is controlled.
Positive displacement reciprocating pumps are characterized by a
fluid enclosure having a slideable piston or flexible diaphragm
mounted therein, and wherein a reciprocating or pulsating movement
is imparted to the piston or diaphragm to change the volume on the
pumping side, and thereby provide a pumping effect. While the
following detailed description is specific to a reciprocating pump
of the diaphragm type, it will be understood that the novel
features of the invention are also applicable to a piston type
displacement pump.
The pump of the present invention finds particular utility as the
circulation pump in an absorption heat pump apparatus. More
particularly, the pump of the present invention may be used in an
absorption heat pump apparatus to convey the solution from the
relatively cool absorber into the heated boiler, the latter being
under a higher pressure than the absorber. To hermetically seal the
solution from the outside atmosphere, the conveying pump typically
comprises a diaphragm type displacement pump, wherein the diaphragm
serves to separate the pumping chamber from the actuation chamber.
The reciprocating motion of the diaphragm, i.e., the pumping motion
of the diaphragm, results from the pulsating pressure of a working
fluid which is applied to the actuation chamber of the pump
housing. Such diaphragm pumps are known in the prior art, note for
example German Auslegeschriften Nos. 1,118,011 and 1,453,579. In
the pumps there described, the pulsating pressure of the working
fluid is generated by piston pumps, and such that the diaphragm
concurrently follows the movement of the piston.
The quantity of the solution being transported in the above
described pumps may be controlled by changing the actuating speed
of the piston pump. The speed control generally uses a three-phase
or AC motor, which however is relatively costly and leads to a
decrease in the overall efficiency of the pump. The conveying
apparatus disclosed in German Auslegeschrift No. 1,453,579 controls
the quantity of the solution being conveyed by the pump by
controlling the quantity of the pressurized oil which is delivered
on each stroke of the piston pump, which in turn is controlled by a
suitable valve arrangement. However, the synchronism between the
stroke of the piston pump and that of the diaphragm pump, as is
usual with all diaphragm pumps which are actuated by piston pumps,
makes it necessary to provide means for compensating for the
unavoidable leaks in the pressurized oil system. For this reason,
the known apparatus for controlling the quantity of the solution to
be conveyed comprises a very complicated valve system, which is not
suitable for continuous operation, such as would be required in the
operation of an absorption heat pump system.
It is accordingly an object of the present invention to provide an
efficient control apparatus for a positive displacement
reciprocating pump which is able to efficiently control the
quantity of the substance being conveyed, and which also avoids the
above noted problems associated with the known pumps of this
type.
It is also an object of the present invention to provide an
absorption heat pump apparatus having an efficient and reliable
circulation pump for the heat carrier solution.
These and other objects and advantages of the present invention are
achieved by the provision of a positive displacement reciprocating
pump which includes a fluid enclosure, and a movable piston means
disposed in the enclosure and sealably dividing the enclosure into
a pumping chamber on one side of the piston means and an actuating
chamber on the other side thereof. An inlet valve and an outlet
valve each communicate with the pumping chamber, and control means
is provided for intermittently supplying a pressurized working
fluid to the actuating chamber so as to intermittently move the
piston means in a direction toward the pumping chamber and thereby
discharge the conveyed fluid from the chamber. The inlet to the
pumping chamber may have a pressure from the fluid being conveyed
which is greater than the pressure of the working fluid, thereby
causing the piston means to perform a return stroke, i.e., an
intake or suction stroke. However, this return stroke may also be
caused by other suitable means, for example, by a spring.
In accordance with the present invention, the actuation chamber of
the enclosure receives a substantially constant flow of the working
fluid, which is delivered by a constant delivery fluid pump. The
working fluid line extending between the constant delivery pump and
the actuating chamber is provided with an outlet, which is
intermittently opened and closed by a control valve.
The constant delivery pump as used in this description is a pump
which is actuated at a constant speed and which provides a constant
delivery rate. The predetermined speed need not be controlled nor
varied during operation. However, a possibility exists that with
some drive motors, their speed may vary slightly at increasing
torque (for example, asynchronous motors), but this is not
considered significant here. It should also be noted that the power
input of the constant delivery pump and its drive motor depends on
the pressure of the working fluid, and when the control valve is
opened, practically no power is consumed.
It will be understood that the above described pulsating action of
the valve is not disclosed in the above referenced German
Auslegeschrift No. 1,453,579, since the valve therein disclosed is
built as a sleeve, which is connected with a rotatable adjusting
knob for axial displacement of the valve. This knob is mounted on a
threaded shaft, and therefore can only be slowly adjusted by hand,
i.e., not pulsatingly.
The pump of the present invention is particularly well suited as a
regulating or metering pump in an absorbtive heat pump system,
since the invention can utilize the pressure potential of the
solution being conveyed, and secondly, it allows for the control of
the control valve apart from the flow of the solution being
conveyed, and thus the control fluid has a low mass, and thus a low
inertia.
The control valve of the pump of the present invention may be
controlled as a function of a measured actual value of a suitable
process parameter. For example, when the pump is used in the closed
cycle of the heat carrier solution in a heat pump, the valve may be
controlled as a function of the heat content of the heat supplying
medium. If exhaust gases or atmospheric air are used as the heat
supplier, its temperature may be measured and the opening and
closing of the control valve controlled as a function of the
measured temperature.
In one embodiment of the invention, the pump is so operated that
the sum total of the opening time and the subsequent closing time
of the control valve forms a working cycle, which remains constant.
Within each working cycle, only the duration of the opening time
and the closing time is controlled as a function of the process
parameter, or the outside temperature of the air, as the case may
be. This embodiment permits a relatively simple construction of the
electric and electronic control for the control valve.
Another embodiment has been found to be advantageous in that it
serves to lengthen the life of the pump. In this case, each working
cycle is composed of a constant opening time and a constant closing
time, and the number of working cycles per unit of time is
controlled as a function of the process parameter or of the outside
temperature of the air. The advantage of this embodiment resides in
the fact that the diaphragm pump and the valve are actuated, and
the constant delivery pump delivers a pressure, only to the extent
required by the measured actual value of the process parameter.
The control valve may be actuated by an electromagnet, which also
contributes to the low inertia of the pump. In one specific
embodiment, the control valve includes a slide having an annular
groove, and the slide is actuated by a magnetic plunger in a
cylinder. When the slide is in its open position, the annular
groove concurrently covers the line from the constant delivery pump
to the control valve, the line from the actuation chamber to the
control valve, and the drain line from the control valve to the
discharge tank. In the closed position, the annular groove covers
the line from the constant delivery pump, as well as the line from
the control valve to the actuation chamber, and the drain line to
the tank is closed.
To avoid exposure of the slide to shock loads, it may be provided
with an impact damping cup, the diameter of which is adapted to the
magnetic plunger. Since the cylinder is filled with hydraulic
fluid, the impact damping cup is also filled with fluid before an
impact by the magnetic plunger, and the oil escapes at an impact
while providing a damping effect. Similarly, the travel of the
slide in its mounting cylinder is defined by a pair of hydraulic
impact damping elements. Thus for example, there may be provided a
impact dampening cup at each end of the slide in the cylinder, and
a corresponding annular lip at each end of the slide. When the
magnetic plunger is withdrawn, the slide is returned to its initial
open position by a spring, so that the constant delivery pump is
again connected to the tank.
A particularly low inertia actuation of the control valve may be
achieved by effecting the opening and closing movements of the
valve by a hydraulic pre-control valve as hereinafter further
described.
Rather than separately actuating the control valve as a function of
a process parameter, the invention also contemplates that the
control valve may be actuated by the movement of the diaphragm of
the pump. In this form of the invention, the pump serves to convey
a gas or liquid at a uniform flow rate. In one embodiment, which is
distinguished by relatively simple structural components, the slide
is held between two springs. One of these springs directly abuts
the diaphragm, thereby biasing the slide in accordance with the
movement of the diaphragm. In a second embodiment, a connecting rod
is used to interconnect the diaphragm and the slide. The slide is
mounted coaxially on the rod, and the rod includes collars on each
side of the slide, with a spring positioned between each end of the
slide and the adjacent collar such that the slide is held on both
sides by these springs. In all of these embodiments, the slide of
the control valve operates with a non-uniform movement. For
example, the slide may be held by a spring which overcomes its dead
center position after an initial movement of the slide. A plate
spring is particularly suitable for use in this manner. The initial
movement of the slide may also be achieved by providing a
correspondingly long idle path of travel for the spring. The
non-uniform movement of the slide may also be controlled by
providing annular grooves and a cooperating ball detent at the
opening and closing positions of the slide.
In yet another embodiment, the operation of the control valve is
effected by the movement of the diaphragm and includes an
interposed hydraulic pre-control system. This pre-control system
has the advantage that greater forces may be applied for the
operation of the control valve. The pre-control valve alternately
connects a pre-control pressure chamber at one side of the slide
with the pump or with the discharge tank. To do so, a pre-control
collar is mechanically connected with the diaphragm of the pump by
means of a connecting rod, while preferably also having an idle or
lost motion therebetween. When the maximum intake stroke is
reached, the diaphragm moves the rod and collar so that the
pre-control chamber of the control valve is opened to the tank so
as to release the pressure of the working fluid therein. When the
diaphragm has reached its maximum delivery stroke, the rod and
collar is moved so that the pre-control chamber of the control
valve is connected with the working fluid pump and is thereby
subjected to its pressure. The rod and collar of the pre-control
system is centered in a neutral position by springs, which are
adjustable, and in such neutral position the precontrol collar
covers and closes the connection to the precontrol chamber of the
control valve.
Some of the objects having been stated, other objects will appear
as the description proceeds, when taken in connection with the
accompanying drawings in which--
FIG. 1 is a schematic illustration of a reciprocating diaphragm
pump and control apparatus, and which embodies the features of the
present invention;
FIGS. 2-4 each illustrate a different embodiment of a control valve
adapted for use with the present invention;
FIGS. 5 and 6 are working diagrams of the control valve and pump of
the present invention;
FIG. 7 is a schematic representation of a reciprocating diaphragm
pump and control apparatus in accordance with the present
invention, and which further includes a hydraulic pre-control
system;
FIGS. 8 and 9 illustrate embodiments of the invention wherein the
movement of the control valve is directly controlled by the
movement of the diaphragm;
FIG. 8a is a force diagram for each of the three springs utilized
in the embodiment of FIG. 8; and
FIG. 10 is a schematic illustration of an absorption heat pump
apparatus which embodies the present invention.
Referring more particularly to the drawing, there is schematically
illustrated at 1 a positive displacement reciprocating pump for
conveying a liquid or gaseous fluid. In the illustrated embodiment,
the pump is in the form of a fluid enclosure 2 having a movable
(i.e. flexible) diaphragm 3 disposed in the enclosure and sealably
dividing the enclosure into a pumping chamber 3.2 on one side of
the diaphragm and an actuating chamber 3.1 on the other side. An
inlet valve 2.1 and a separate outlet valve 2.2 each communicate
with the pumping chamber 3.2 of the enclosure.
As further described below, the above diaphragm pump 1 may be
interposed in a heat carrier system, for example, as a solution
pump in an absorptive heat pumping system as illustrated in FIG.
10. In such case, the pressure at the inlet 2.1 normally exceeds
atmospheric pressure, and serves to move the diaphragm 3 during the
intake or return stroke.
The pumping action of the diaphragm pump 1 results from the
reciprocal motion of the diaphragm 3. More particularly, the
actuation chamber 3.1 receives, via lines 8.1 and 8.2, a
pressurized working fluid (typically oil) from the constant
delivery pump 4, which may be a gear pump or a multicylinder piston
pump. The pump 4 is designed to operate at a constant speed, and
also deliver a substantially constant flow rate. An electric motor
5 drives the pump 4 at a constant speed. Lines 8.1 and 8.2 have a
bypass line 7, which can be opened or closed by the control valve
6. The control valve 6 is actuated by an electromagnet 9, which may
be controlled by a control system 10.1, and a measuring device or
sensor 10.2 which monitors a process parameter, such as a
temperature sensor for monitoring the outside temperature of the
air. The opening and closing of the valve 6 alternately releases
and applies pressure to the actuation chamber 3.1. When the valve 6
is closed, the conveying pressure of the pump 4 overcomes the
pressure in the outlet line 2.2 of the pumping chamber 3.2, to move
the diaphragm through its discharge stroke. When the valve 6 is
opened (as illustrated in FIG. 1) and thus the pressure released in
the lines 8.1 and 8.2, the pressure in inlet line 2.1 pushes the
diaphragm in the opposite direction, which corresponds to its
intake or suction stroke. The entire control valve may be
accommodated in a tank 11 as shown in FIG. 1, which is provided
with a seal 13 for the shaft 12 of the motor 5, as well as with
outlets for the control line to the electromagnet 9 and the
pressure line 8.2. Also, a conventional pressure relief valve 14
may be positioned in the line 8.1.
FIG. 2 illustrates an embodiment of the control valve 6 which is
adapted for use with the present invention. As there shown, the
valve 6 includes a slide 17 which is axially displaced in the
cylindrical bore 19 of a valve housing 20. A spring 21 biases the
slide to the left, and a plunger 16 of electromagnet 15 is adapted
to move the slide to the right. Slide 17 has an annular groove 18,
and in the illustrated position, the groove 18 overlies connecting
duct 22 which comes from the pump 4, and connecting duct 23 which
leads to the tank 11, as well as connecting duct 24 which leads to
the actuation chamber 3.1 of the diaphragm pump. Thus when the
slide 17 is in the illustrated position, the oil stream delivered
by the pump 4, and also the oil stream returned by the diaphragm
during its intake stroke, flow off into tank 11. When the magnet 15
is energized, the plunger 16 pushes the slide 17 to the right,
until the annular groove 18 overlies only the duct 22 from the pump
4 and the duct 24 to the actuation chamber 3.1. In this position,
the actuation chamber 3.1 is subjected to the pressure of the
working fluid from the pump 4, and the diaphragm performs its
delivery stroke. To avoid shock loads on the slide 17, annular
damping cups 25 are arranged at both ends of the bore 19, and the
slide 17 includes mating damping lips 26 which move into the cups
25. Since the bore 19 is filled with oil on both front faces of the
slide 17, which flows through the central axial bore 28, the lips
26 push the oil slowly out of the cups 25 to soften the impact. To
soften the impact of the plunger 16 on the front face of the slide
17, there is provided an impact damping cups 27, which has a
diameter substantially adapted to that of the plunger 16. By this
arrangement, the impact of the plunger is hydraulically
absorbed.
FIG. 3 shows a control valve in the form of a diaphragm valve with
a flexible membrane 29 which is reciprocated by plunger 30 and
magnet 31. As it does so, the closing lip 32 alternately opens or
closes the drain pipe 33, which connects valve chamber 34 with the
tank 11. The connection 22 leads from the pump 4, whereas the
connection 24 is connected to the actuation chamber 3.1 of the
diaphragm pump. An overflow passage 36 connects the pressure relief
chamber 35 of the valve with the valve chamber 34.
The control valve shown in FIG. 4 is also a diaphragm valve, which
is generally the same as the embodiment shown in FIG. 3, and
wherein the membrane 29 is acted upon in the control chamber 37,
via the overflow passage 36, by the pressure present in the chamber
34. However, the control chamber 37 may also be connected, via the
connection 38, valve 39, plunger 40 and electromagnet 41, with the
tank 11 so that the pressure in the control chamber 37 will drop
when the valve 39 is opened. It should be noted that the cross
section of outlet 38 is greater than the cross section of the
overflow passage 36. Thus when the pressure decreases in the
control chamber 37, the membrane will lift from the closing cross
section of the drain line 33, and when the valve 39 closes, the
pressure increases again and the diaphragm closes against the drain
line 33.
FIG. 5 illustrates a working diagram of the control valve 6 and
pump 1. More particularly, FIG. 5 illustrates an embodiment wherein
the delivery volume may be decreased from stroke to stroke as a
function of a suitable process parameter, such as, for example, the
outside temperature of the air.
As illustrated in FIG. 5, the control valve 6 is actuated in a
working cycle A which is constant per unit of time. Each working
cycle A includes a closing time C and an opening time O, of the
valve 6. The pump 1 defines a delivery stroke time DS, and a return
stroke time RS, and, if necessary, and idle time I. Since the
stroke velocity of the diaphragm pump 1 is primarily determined as
a function of pressure, both the delivery and return stroke of the
pump 1 may be carried out at a constant velocity. However, the
length of each stroke is influenced by the control of the opening
and closing time of the control valve 6. When closing time C of the
valve 6 takes the entire time which is necessary for the delivery
stroke, the diaphragm of the pump 1 performs its maximum delivery
stroke H Max. When the closing time is less, a working cycle of the
pump 1 includes the delivery stroke DS, the duration of which
corresponds to the closing time C, as well as the return stroke
time RS and idle time I. The sum of RS and I corresponds to the
opening time O of the control valve 6. As can be seen in FIG. 5,
the sum of the opening time O and closing time C of the control
valve 6 remains constant, and the ratio of the return stroke time
RS and the delivery stroke time DS remains constant. The duration
of the closing time C and thus the magnitude of the delivery
stroke, however, may be varied within each working cycle A, and
thus also may be varied the quantity delivered by the pump 1.
In the control diagram of FIG. 6, the diaphragm pump 1 is actuated
only in two operating conditions. In one operating condition, the
pump operates at a maximum stroke H Max, and in the other condition
the pump is idle. In this mode of operation, the idle time I is
preferably an integral multiple of the working time A, which
consists of a delivery and a return stroke. The duration of the
idle time I is controlled as a function of the process parameter,
such as for example, the outside temperature of the air. To perform
the delivery stroke, the control valve 6 is closed. While the
return stroke is performed, and while the pump is idle, the control
valve 6 is opened.
FIG. 7 illustrates an embodiment of the invention in which the
control valve 6 is controlled by the movement of the diaphragm 3 of
the pump 1, with a hydraulic pre-control system being interposed
therebetween. Slide 17 of the control valve 6 receives a
pre-control pressure on its collar 50 in the pre-control chamber
52, and the slide may thereby be biased against the force of the
spring 53. The resulting movement of the slide is limited by the
sleeve 54. Spring 53 is operative on the control slide 17 to
periodically move the slide to the left and to the dashed line
position as shown in FIG. 7, and wherein the bypass line 7 and line
57 to the valve 61 are opened, and the tank outlet 58 of the valve
6 is closed. A pressure in the pre-control chamber 52 is operative
to periodically move the valve to the right to the illustrated
solid line position, wherein the bypass line 7, the line 57, and
the tank outlet 58 are all opened to each other, so that the
pressure drops to the tank pressure in the line system 8.1 and 8.2
to the diaphragm pump 1 and in the line 57 to the valve 61.
The pressure in the pre-control chamber 52 is controlled by the
pre-control valve 61, which includes a cylindrical valve housing 90
communicating with the actuating chamber 3.1 of the pump 1 and
extending along a direction aligned with the direction of movement
of the diaphragm 3. A rod 69 is coaxially mounted in the valve
housing, and the rod 69 mounts two axially spaced apart collars 62
and 63 which slideably mount the rod and collars within the valve
housing. Also, one end of the rod is operatively connected to the
diaphragm 3 by a lost motion interconnection means as further
described below. Three fluid lines communicate with the valve
housing, namely the line 91 leading from the valve housing outlet
66 to the pre-control chamber 52, the line 57 leading from the
outlet 67 to the pump 4 via the lines 7 and 8.1, and the line 92
leading from the outlet 68 to the discharge tank 11. The collar 63
covers the outlet 66 and is centered by springs 64 and 65 in the
illustrated neutral position. Also, an adjusting screw 70 is
mounted in the end of the valve housing for adjusting such neutral
position.
The lost motion interconnection means between the diaphragm 3 and
rod 69 includes an apertured disc 71 mounted on the diaphragm,
together with a closed cap 72 into which the piston rod 69 extends.
A ring 74 is attached to the end of the piston rod, which ring is
sized to engage the apertured disc 71, since the diameter of the
ring 74 is larger than the aperture in the disc 71.
To now describe the operation of the pump 1 as illustrated in FIG.
7, it will be understood that in the illustrated solid line
position of the slide 17 of the control valve 6, the pump 4
delivers a pressurized working fluid via line 8.1, bypass line 7,
and tank outlet 58, to the tank 11. Inlet 57 is also connected with
the tank outlet 58. The pressure of the fluid being conveyed by the
pump 1 enters via inlet 2.1 into the pumping chamber 3.2, and the
diaphragm 3 moves from its illustrated position to the right.
Pre-control valve 61 with collar 63 closes the outlet 66 in the
illustrated position. Thus the working fluid in the pre-control
chamber 52 cannot escape. Nor can the spring 53 push the slide 17
to the left. However, when the diaphragm reaches the area of its
maximum intake stroke, the cap 72 pushes against the end 75 of the
piston rod 69 and moves the control collar 63 to the right. This
connects the outlet 66 with the tank connection 68, and the
pressure in the pre-control chamber 52 of the valve 6 collapses. As
a result, the spring 53 now moves the control slide 17 to the left,
until tank outlet 58 is closed. The slide 17 is then in the dashed
line position, and as a result, the pressure of pump 4 builds up in
line system 8.1 and 8.2 as well as in line 7, and also at the inlet
67 of the pre-control valve 61. The throttle 87 in the line 8.2
delays the pressure buildup in the actuation chamber 3.1.
The pressure supplied by the pump 4 moves the diaphragm toward the
left, and the fluid being conveyed by the pump 1 is discharged
through the outlet 2.2. In the area of the maximum discharge stroke
of the diaphragm, the apertured disc 71 engages the ring 74, and
moves the control collar 63 to the left and until outlet 66 is
connected with inlet 67. This results in the buildup of the working
fluid pressure in chamber 52 of the control valve 6, and the slide
17 is pushed to the right to its original position. This in turn
causes the pressure to collapse in the line system 8.1, 8.2 and 7,
as well as in actuation chamber 3.1. The diaphragm thereby starts
another cycle, and as it does so, after a short movement of the
diaphragm, the control collar 63 again covers the outlet 66, so
that control slide 17 can no longer move to the left due to the
fluid which is contained in the chamber 52. The drop in pressure
can be influenced by a throttle 89 in the line 58.
In the embodiment shown in FIG. 8, the slide 17 of control valve 6
includes a central axial bore 80 to relieve any pressure acting on
its ends. Thus the slide 17 is movable in the valve housing and is
held at its end faces by springs 76 and 77 in a neutral position,
in which the bypass line 7 is connected via inlet 57 to the tank
outlet 58. Spring 76 abuts the diaphragm of the pump 1 via a
supporting plate 81. The movement of the slide 17 to the left as
illustrated, is limited by stop 55. Movement is also opposed by an
annular spring plate 78, which is mounted in the annular channel 79
of the valve housing. In the indicated position of the control
slide 17, no pressure is exerted on the actuation chamber 3.1. As a
result, the fluid being conveyed is admitted through inlet 2.1, and
the diaphragm moves to the left. This movement increases the force
of spring 76, until it is in a position to overcome the sum of
spring force 77 and spring force 78. In doing so, the spring plate
78 passes its dead center position, so that it thereafter assists
in the movement of the slide to the left and counteracts spring 77.
This results in the slide 17 moving in a non-uniform manner to the
left, and the slide closes inlet 57. As a result, pressure then
builds up in the actuation chamber 3.1 and the diaphragm is
displaced to the right, resulting in the force of the spring 76
being reduced. This movement continues until the force of the
spring 77 is greater than the sum of the spring force 76 and the
spring force 78. At this point, the spring plate 78 again passes
its dead center position, and the slide 17 moves in a non-uniform
manner to the right, thereby connecting inlet 57 with outlet 58.
The pressure in the actuation chamber 3.1 thereby collapses, and
the fluid being conveyed again enters into the pumping chamber 3.2
through inlet 2.1.
The spring force diagrams as shown in FIG. 8a represent the spring
forces F for the springs 76, 77, and 78, which are exerted on the
control slide 17 during movement of the diaphragm.
The embodiment shown in FIG. 9 differs from that of FIG. 8 only in
that the slide 17 of valve 6 is coaxially and slideably mounted on
a connecting rod 82. The rod 82 is in turn fixed to the diaphragm
of the pump 1. Also, the rod 82 mounts a pair of springs 76 and 77,
between which the control slide 17 is located. A further difference
consists in that the operative positions of the slide are
determined by annular grooves 85 and 86, which cooperate with a
ball detent 84 and spring 83 in the valve housing. In the
illustrated position of the slide 17, the ball 84 engages the ring
85, and the working fluid delivered by the pump 4 is guided through
bypass line 7 to the tank 11. As a result, the conveyed fluid,
being under a higher pressure, moves through inlet 2.1 into the
pumping chamber 3.2 and moves the diaphragm and connecting rod 82
to the left. This increases the force of spring 76, until the
holding force provided by the spring 83 and ball detent 84 has been
overcome. When this occurs, the slide 17 moves to the left relative
to the diaphragm, until the groove 86 is engaged by the ball 84. In
this position, the pump inlet 57 is separated from the outlet 58,
resulting in the pressure building up in the actuation chamber 3.1,
so that the diaphragm moves to the right and discharges the
conveyed fluid through the outlet 2.2. As it does so, the force of
spring 77 increases, until the force is sufficient to abruptly move
the slide 17 to the position wherein the groove 85 is again engaged
by the ball 84.
If desired, a spring 73 as shown in FIG. 8 can be provided in all
of the disclosed embodiments, to compensate for the various forces
which are operative on the diaphragm. However, it can also be
sufficiently strong so that it operates as a return stroke spring.
A return stroke spring is intended to displace the diaphragm so
that the conveyed fluid is sucked in through the inlet 2.1. If such
a return stroke spring is provided, the pump 1 according to this
invention may be used for conveying a substance having a pressure
at the inlet 2.1 which is not or not substantially higher than the
tank pressure.
FIG. 10 illustrates the pump 1 of the present invention utilized as
the circulation pump for the solution in an absorptive heat pump
system. In the illustrated example, the heat pump system includes a
boiler or generator which is heated by electricity or the like, and
which is filled with water containing a high concentration of
dissolved ammonia. When this solution is heated, the ammonia is
driven off as a vapor and the water remains behind. As the
evaporation of the ammonia continues, the pressure rises until it
is high enough to cause the ammonia vapor to condense in the
condenser. The condensed liquid ammonia passes through the
expansion valve and thereupon evaporates again, absorbing heat as
it does so. The water which remains behind in the boiler is passed
through a heat exchanger, where it loses some of its heat. The
water then goes to the absorber, where it again absorbs the ammonia
vapor coming from the evaporator. The thus formed ammonia solution
is pumped back through the heat exchanger by the circulation pump
1, and the cycle is repeated.
In the drawings and specification, there has been set forth a
preferred embodiment of the invention, and although specific terms
are employed, they are used in a generic and descriptive sense only
and not for purposes of limitation.
* * * * *